Limb-Shaking Transient Ischemic Attacks in a Patient with Previous Bilateral Neck Irradiation: The Role of Collateral Flow.

Nasopharyngeal carcinoma (NPC) is commonly treated with bilateral neck radiation, which is closely associated with the complication of carotid-occlusive disease. This leads to cerebral hemodynamic compromise and possible ischemic stroke. Another manifestation is limb-shaking transient ischemic attacks (LS-TIAs), characterized by rhythmic jerks which can be easily mistaken as a focal motor seizure. We describe a case of unilateral LS-TIAs from bilateral carotid occlusion that resolved with contralateral carotid revascularization. Our patient is a 65-year-old gentleman who had no significant co-morbidities other than a past history of bilateral neck irradiation for NPC 8 years before. He presented with left-sided limb weakness and subsequently left-sided limb involuntary movements whenever he sat up or stood. His symptoms did not respond to anti-epileptic therapy. Clinical and neurological examination was significant for a left pronator drift and weak left finger abduction. Computed tomography and magnetic resonance imaging of the brain revealed infarcts in the right periventricular and watershed areas; MR angiogram showed bilateral internal carotid artery occlusion. Single photon emission computed tomography showed reduced blood flow in the right frontal, temporal, and parietal regions, that reduced further after acetazolamide challenge. He was diagnosed as having LS-TIA secondary to carotid-occlusive disease. Attempts at endovascular opening the right internal carotid artery failed. Following successful left carotid angioplasty and stenting, his symptoms gradually resolved. The left internal carotid artery remained patent at the 3-month follow-up; the right side remained occluded. Our case supports the hypothesis that LS-TIAs are due to hemodynamic compromise and may respond to improved collateral cerebral blood flow.